Supercritical fluid extraction of cholesterol from liquid egg yolk

Abstract

A method for extraction of cholesterol from untreated yolk with supercritical carbon dioxide. The supercritical carbon dioxide extraction of cholesterol from the liquid egg yolk is performed in the presence or absence of cosolvents or other agents enhancing the cholesterol extraction. All agents are non-toxic and safe for human consumption.

What is claimed is: 
     
       1. A method for supercritical fluid extraction of at least 55% of cholesterol by weight from intact untreated liquid egg yolk having about 50% moisture and pH 6.0-6.6, said method comprising steps: (a) contacting the untreated liquid egg yolk with a vegetable oil in a ratio from 1 volume of egg yolk to 0.5 to 4 volumes of oil;   (b) homogenizing a mixture of step (a) at about 20,000 to 25,000 rpm for about 15-45 minutes;   (c) extracting the homogenate of step (b) with supercritical carbon dioxide at an extraction pressure of between about 2,000 and 4,500 psig and at a temperature between 31° C. and 45° C., having a solvent to feed ratio from 50:1 to 100:1; and   (d) separating the liquid egg yolk from the supercritical carbon dioxide containing extracted cholesterol and the vegetable oil used in step (a).   
     
     
       2. The method of claim 1, wherein the vegetable oil is selected from the group consisting of safflower oil, peanut oil, olive oil, corn oil, sunflower oil, cotton oil and soybean oil. 
     
     
       3. The method of claim 2 wherein the vegetable oil is soybean oil. 
     
     
       4. The method of claim 3 wherein the liquid egg yolk and vegetable oil are in ratio 1:2, volume/volume. 
     
     
       5. The method of claim 4 wherein the extraction pressure is from 3,000 to 4,000 psig and temperature is between 35° C. and 40° C. 
     
     
       6. The method of claim 5 wherein the pressure is 3,500 psig and temperature is 35° C. 
     
     
       7. The method of claim 6, wherein the supercritical carbon dioxide additionally contains a cosolvent selected from the group consisting of food grade ethanol, methanol, propanol and a mixture thereof added in amount from 1% to 10%, volume/volume, of cosolvent to solvent. 
     
     
       8. The method of claim 7, wherein the cosolvent is ethanol present in amount from 1% to 5% volume/volume of the cosolvent to the solvent. 
     
     
       9. The method of claim 8, wherein the cosolvent is ethanol added in amount of 1% of volume of the solvent. 
     
     
       10. The method of claim 7, wherein the cosolvent is methanol present in amount from 1% to 10% volume/volume of the cosolvent to the solvent. 
     
     
       11. The method of claim 10, wherein the cosolvent is methanol added in amount of 1% of volume of the solvent. 
     
     
       12. A method for supercritical fluid extraction of at least 55% of cholesterol by weight from intact untreated liquid egg yolk having pH between 6.0 and 6.6 and containing about 50% moisture, said method comprising steps: (a) contacting the untreated liquid egg yolk with soybean oil in a ratio about 1:2, volume/volume;   (b) homogenizing a mixture of step (a) for about 15-45 minutes at 20,000-25,000 rpm;   (c) extracting the homogenate of step (b) with supercritical carbon dioxide at extraction pressure about 3,500 psig and at temperature between 35° C. and 40° C. having a solvent to feed ratio from 50:1 to 100:1;   (d) repeating step (c) one to five times; and   (e) separating the liquid egg yolk from the supercritical carbon dioxide containing extracted cholesterol and the oil used in step (a).   
     
     
       13. The method of claim 12 wherein the supercritical carbon dioxide additionally contains a cosolvent selected from the group consisting of food grade ethanol, methanol, propanol and a mixture thereof added in amount from 1% to 10%, volume/volume, of cosolvent to solvent. 
     
     
       14. The method of claim 13, wherein the cosolvent is ethanol present in amount from 1% to 5% volume/volume of the cosolvent to the solvent. 
     
     
       15. The method of claim 13, wherein the cosolvent is methanol present in amount from 1% to 5% volume/volume of the cosolvent to the solvent. 
     
     
       16. A method for supercritical fluid extraction of at least 55% of cholesterol by weight from intact untreated liquid egg yolk containing about 50% moisture and having pH from 6.0 to 6.6, said method comprising steps: (a) contacting the untreated liquid egg yolk with soybean oil in a ratio of 1:2 volume/volume;   (b) homogenizing a mixture of step (a) for about 15-45 minutes at 20,000-25,000 rpm;   (c) extracting the homogenate of step (b) with supercritical carbon dioxide containing from 1% to 10% ethanol at extraction pressure about 3,500 psig and at temperature between 35° C. and 40° C. having a solvent to feed ratio of from 50:1 100:1; and   (d) separating the liquid egg yolk from the supercritical carbon dioxide containing extracted cholesterol and the vegetable oil used in step (a).   
     
     
       17. The method of claim 16 wherein step (c) is repeated one to five times. 
     
     
       18. A method for supercritical fluid extraction of at least 55% of cholesterol by weight from intact untreated liquid egg yolk containing about 50% moisture and having pH from 6.0 to 6.6, said method comprising steps: (a) contacting the untreated liquid egg yolk with soybean oil in a ratio of 1:2 volume/volume;   (b) homogenizing a mixture of step (a) for about 15-45 minutes at 20,000-25,000 rpm;   (c) extracting the homogenate of step (b) with supercritical carbon dioxide containing from 1% to 10% of methanol at extraction pressure about 3,500 psig and at temperature between 35° C. and 40° C. having a solvent to feed ratio of from 50:1 to 100:1; and   (d) separating the liquid egg yolk from the supercritical carbon dioxide containing cholesterol extracted into the oil.   
     
     
       19. The method of claim 18 wherein step (c) is repeated one to five times. 
     
     
       20. The method of claim 1 wherein the step (c) is repeated one or more times.